1. Field of the Invention
The present invention relates to a zoom interlocking mechanism which varies a viewable field angle of a zoom finder device and an illuminating angle of a flashlight in cooperation with a zoom lens assembly.
2. Background Arts
A camera with a zoom lens assembly usually has a zoom finder device. In the zoom finder device, variator lenses move simultaneously with zooming of the zoom lens assembly in order to vary a viewable field angle of the zoom finder device. Also is known a zoom flash device which varies an illuminating angle of a flashlight in cooperation with the zooming of the zoom lens assembly, in order to make efficient use of the flashlight even when the zooming changes photographic field angle.
A zoom interlocking mechanism, which is disclosed in Japanese Laid-Open Patent Application No. 10-186480 (corresponding to U.S. Pat. No. 6,072,954), is provided with an arc-shaped gear and a cam disposed along a periphery of a movable lens barrel rotated with zooming. With the arc-shaped gear is engaged a drive gear for rotating the movable lens barrel and a gear train for moving a flash projector in a zoom flash device back and forth. There is provided a pair of flat gears engaged with each other in a basic portion of the flash projector. Both outer sides of the flat gears are engaged with a pair of rack gears formed in inner walls of a frame of the flash projector. One of the flat gears is engaged with an output gear of the gear train. Rotation of the movable lens barrel transmitted through the gear train rotates the pair flat gears in opposite directions each other, so that the flash projector is moved back and forth in an optical axis direction through the pair rack gears. Also the cam in the movable lens barrel moves variator lenses in a zoom finder device. Thus, an illuminating angle of the zoom flash device and a viewable field angle of the zoom finder device are changed at the same time in cooperation with the rotation of the lens barrel.
In the above zoom interlocking mechanism a gear train having a lot of gears is provided between the periphery of the movable lens barrel and the flash projector. Therefore, the zoom interlocking mechanism makes a camera high cost and large size because of an installation space for the gear train. There is a disadvantage in that the interlocking mechanism cannot be applied to a compact and low cost camera.
An object of the present invention is to provide a zoom interlocking mechanism at low cost which has a simple structure so as to be disposed in small space.
To achieve the above and other objects, a zoom interlocking mechanism according to the present invention comprises a zoom lens assembly having a zoom lens optical system which moves back and forth in an optical axis direction for varying a focal length thereof system; a zoom finder device holding plural variator lenses which are movable in the optical axis direction; a flash projector installed movably in the optical axis direction; and a cam plate which is disposed horizontally inside a camera, and movable in a direction of perpendicular to the optical axis and horizontal to the camera.
The cam plate comprises a rectangular plate portion and a rack gear formed integrally with the plate portion. A groove used for interlock with a lens barrel is formed in one surface of the plate portion, and grooves used for interlock with the variator lenses for changing a viewable field angle of the zoom finder device are formed in the other surface. The rack gear extends to a moving direction of the cam plate, and has the same thickness as the plate portion. The rack gear rotates plural flat gears. These flat gears are engaged with other rack gears formed in the flash projector so as to vary a position of the flash projector.
According to the present invention, it is possible to compose the zoom interlocking mechanism in the simple structure which varies the viewable field angle of the zoom finder device and an illuminating angle of a flashlight in cooperation with zooming. Moreover, because the cam plate can be formed in a thickness of approximately 1 mm, it is possible to dispose the zoom interlocking mechanism in small space. The present invention will help miniaturization of the camera.